1. Field of the Invention
The present invention relates to a ramp that evacuates a transducer from a data storage medium while a rotary-disk type data storage device such as a magnetic-disk storage device stops its operation.
2. Description of Related Art
A ramp loading/unloading method is a method which positions a transducer to an evacuation area while a rotary-disk type data storage device such as a magnetic-disk storage device stops its operation. FIG. 1 is a plan view of a conventional magneticdisk storage device 10 found in the prior art which includes the ramp loading/unloading method. A housing 11 houses magnetic disks 17, a rotary actuator assembly 12, a voice coil motor 16, and a ramp 20 and forms hermetic space interiorly. The magnetic disks 17 consist of a plurality of stacked disks which are fastened to a spindle 18. Each disk is rotated with the spindle 18 by a spindle motor (not shown). Both sides of the magnetic disk 17 are used as data recording surfaces. A plurality of stacked suspension arms 14 are coupled to the actuator assembly 12 in correspondence with the number of the data recording surfaces of the magnetic disks 17. Each suspension arm 14 has a slider 19 attached to the front end portion, and a magnetic head (not shown) for scanning the recording surface of the disk is mounted on the slider 19.
The actuator assembly 12 is rotated about a pivot shaft 13 by the voice coil motor 16 so that the slider 19 is positioned over the surface of the magnetic disks 17 and on the ramp 20. The suspension arm 14 is formed from elastic material, and elastic force is applied in the direction where each slider 19 approaches the surface of the disks 17. The rotation of the magnetic disks 17 creates a thin cushion of air that floats the slider 19 off the disk surface, and the floating force and the elastic force applied to the suspension arm 14 are balanced so that the slider 19 maintains a constant distance from the surface of the magnetic disks 17 during rotation. The ramp 20 is arranged near the magnetic disks 17 so that a part of the ramp 20 engages the disks.
FIG. 2 is a perspective view of the ramp 20 shown in FIG. 1. The ramp 20 has a supporting portion 21 and a sliding portion 22 protruding horizontally from the supporting portion 21. The ramp shown in FIG. 2 supports two suspension arms, and correspondingly, the upper and lower recording surfaces of a single magnetic disk. Therefore, in the case where a plurality of magnetic disks are provided, a plurality of ramps with the structure shown in FIG. 2 will be stacked and joined with one another. This ramp is provided with three guiding zones 23 and a landing zone 24 on the upper side of the sliding portion 22. These zones are also formed on the lower side of the sliding portion 22 symmetrically with respect to an X-Y plane horizontally dividing the magnetic disks 17 into two parts. An opening 25 engages the magnetic disks 17 in the state where the ramp 20 is mounted in the magnetic-disk storage device, and the suspension arm 14 is unloaded from the disk surface to the landing zone 24 through some position on the front boundary 26 of the guiding zones, or is loaded from the landing zone 24 onto the disk surface.
When the suspension arm 14 is disengaged from the ramp 20, the position on the magnetic disk 17 where the suspension arm 14 is loaded is important. A dedicated track is formed at the first position on the magnetic disk 17 where the suspension arm 14, disengaged from the ramp 20 after breaking contact with the ramp 20, is positioned. The dedicated track is not used as a recording area and fulfills a role of preventing the loaded slider 19 from destroying recorded data by touching the magnetic disk 17. The suspension arm 14, therefore, needs to land from the ramp 20 onto the magnetic disk 17 at an accurate position. The suspension arm 14 rotates while contacting the guiding zone 23 and the landing zone 24 in a Y-axis direction shown in FIG. 2. The guiding zone 23 extends upward, then flat, and finally downward to the landing zone 24 in the direction from the front boundary 26 to the landing zone 24. The landing zone 24 is adjacent to the upwardly inclined guiding surface 23 and the supporting portion 21, and also the suspension arm 14 is given elastic force in a direction where the arm 14 is pushed against the landing zone 24. Therefore, even if impact force were applied to the actuator assembly 14, there would be no possibility that the suspension arm 14 positioned at an evacuation position on the landing zone 24 would be moved out of the landing zone 24.
FIG. 3 is a sectional view of the ramp 20 and the suspension arms 14 engaging the ramp 20, taken substantially along line A--A of FIG. 1. Blocks 21 are stacked and formed into the single ramp 20, which can evacuate four suspension arms 14 corresponding to two magnetic disks 17. The suspension arm 14 contacts the guiding zone 23 of the ramp 20 through a dimple 15 mounted on the suspension arm 14. A front portion 27 protrudes from the guiding zone 23, as shown in FIG. 3. The purpose of this is to reduce the frictional force between the dimple 15 and the guiding zone 23 and also define a mutual contact position so that a smooth sliding motion of the dimple 15 is obtained when the dimple 15 passes through the boundary between the guiding zones 23 and the boundary between the guiding zone 23 and the landing zone 24.
FIG. 4 illustrates the sectional configuration of another conventional ramp found in the prior art. Even in this example, a guiding zone 23 is formed with a protruding portion 27 that a dimple 15 contacts. Furthermore, FIG. 5 shows a plan view of the ramp shown in FIG. 3 or 4. As shown in FIG. 5, the width of the guiding zones 23 and landing zone 24 of the ramp 20 is defined by two outer and inner circular arcs having the pivot shaft 13 as a center. The boundary between the guiding zones 23 and the boundary between the guiding zone 23 and the landing zone 24 are defined by lines passing through the pivot shaft 13, respectively.
The sliding portion 22 of the ramp 20 shown in FIG. 3 or 4 has both the protruding peripheral portion 27 and the sunken landing zone 24 surrounded by the guiding zone 23 and the supporting portion 21, and furthermore, the circular arc-shaped inner peripheral portion 27 of the guiding zones 23 and the landing zone 24 is shorter than the circular arc-shaped outer peripheral portion 28, as shown in FIG. 5. Therefore, in the case where a ramp and a plurality of sliding zones 22 are molded in one body by a casting mold, the direction in which the casting mold is pulled out cannot be obtained. For this reason, the ramp needs to be divided into a plurality of blocks and molded, and each molded block needs to be assembled by bonding them together. Consequently, since an assembly error is added to an error in the molded dimension of each block, it becomes difficult to determine the accurate landing position of the slider 19 and therefore the width of the dedicated track needs to be widened for compensating the errors. The dedicated track area is a non-recording area, so it wastefully consumes the magnetic disk. For this reason, the dedicated track area needs to be narrowed in every possible way.
In view of the prior art described above, it therefore can be seen that there is a need to provide a ramp for a data storage device which is high in fabrication accuracy and can be easily mounted in the data storage device.